Converter of angular shaft position into a serial code



Oct. 11, 1966 v. I. VLASENKO ETAL 3,278,927

CONVERTER OF ANGULAR SHAFT POSITION INTO A SERIAL CODE Filed March 25, 1963 United States Patent Filed Mar. 25, 1963, Ser. No. 268,520 1 Claim. 01. 340-347 This invention relates to optical converters of a shaft position to a pulse serial code.

The present methods of collecting data on technological processes are insufliciently reliable and do not ensure the desirable accuracy; therefore their application, to closedcircuit control systems, used at automatically-controlled manufacturing plants is diflicult in operation.

For the same reasons the process of introducing control computers into service is also proceeding at a slow pace.

Conventional converters of angular shaft position proportional to the value of a technological process parameter (for instance, pressure, liquid flow rate, temperature and etc.) are not suitable for the automatization of manufacturing processes primarily owing to their considerable cost due to the utilization of the parallel code generated by a large number of sensitive elements.

In conventional optical converters the parallel code is generated by a group consisting of 10 to 18 independent photoelectrical cells suitably located in the area.

When it is necessary to control a number of parameters many converters are required which in turn render the data collecting system more complex and therefore more costly.

In order to avoid said disadvantages, use is made in the converter of an optical system to compress the code pattern to project it onto a mirror mounted on a loop (frame) or on a relay armature and designed to spatially scan the two-dimensional code pattern with the help of a single photodiode. The relay winding and gas-discharge tube of the converter are set triggered operation, decreasing power consumption and increasing the span life of the system components.

As a result of this the converter generates directly on its output terminals a pulse serial code.

The transmission of such a code requires only the use of a shielded single-wire arc cable and consequently the cost of the telemetrie line wires considerably decreases.

The cost of the converter itself also decreases as the number of the photocells used in it is reduced to one.

FIG. 1 shows a plan view of one variant realization of the converter referred to in the present invention.

FIG. 2 is a diagrammatic representation of the automatic scanning synchronization by a gas-discharge tube flash.

FIG. 3 shows diagrams, as a function of time, of the light flow radiated by the discharge tube, of the current flowing through the discharge tube and of the angular scanning frequency.

A coding disk consisting of transparent and opaque elements is mounted on a controlled shaft 2.

A pulse gas discharge tube 3 serves to generate a light flow and to control the current flowing through the loop or through the relay winding. The light passes through a sampling slot (aperture) 4 and exposes the coding disk 1. A tubular lens 5 transfers the parallel light beam into a convergent light :beam, incident upon a mirror 6 mounted in a rotating frame 7 which is placed in the magnetic field of a permanent magnet 8. A photodiode 9 in conjunction with a diaphragm 10 receives the light beam reflected by the mirror 6 and generates an output signal in the form of a pulse serial code available at the output terminals 11. The mirror can also be fixed on a electromagnetic relay armature.

Operation of the converter proceeds as follows. In

order to register at a given moment the readings of the instrument from a data collecting center a command pulse is fed to the terminals 12 of the converter. This pulse is app-lied through a circuit 13 to the pulse tube 3. A pulse from the output of the circuit 13 applied to the tube 3 ignites it and the current pulse from it is fed to the winding on the frame 7, causing its the rotation together with the mirror 6 which produces the optical scanning of the two-dimensional code pattern read out on the disk. V The optical scanning is to be effected only within a short period of time, when the gas-discharge tube radiates light beams and therefore in this system an extremely simple and stable circuit of the 'automatical scanning is employed synchronized to the moment of the tube of the flash.

This is achieved by connecting the loop (or the relay winding) in series with the pulse tube and resulting in that the current from the power source 14, passing through the glowing tube, actuates the mechanical control system of the optical scanning. As shown in FIG. 3 the light beam F produced by the tube and the current I flowing through it, coincide as to time while the angular scanning frequency coincides with the current passing through the loop (or the relay winding) thus ensuring reliable synchronization.

A bright flash of the tube 3 produces a light beam samples by the narrow slot 4. The coding disk 1 depending upon the angular shaft position modulates accordingly the light beam, which is transformed by lens 5 into a convergent light beam incident upon the mirror 6.

When tube 3 flashes, the picture of the small radially mounted portion of the code disc is focused through lens 5 on mirror 6 and is projected as a two-dimensional image of one code on the plane of diaphragm 10. When the mirror is rotated, this two-dimensional image moves, and the slot of diaphragm 10 permits successive passage of beams having intensity equal either zero or maximum in accordance with the code, arranged radially of the optically scanned portion of the code disk at a particular or predetermined radial level of the code or disk.

As a result of rotation of the mirror 6 separate light beams of the various intensities pass successively via the diaphragm 10 and expose the photodiode 9. Simultaneously on the terminals 11 there appears a sequence of pulses reproducing the combination of transparent and opaque segments of the coding disc.

This pulse sequence can be further amplified and transmitted to a certain distance over the telemetric line.

At the control center where the data processing computer is stationed this sequential pulse combination is read into a shift register and then transferred in the form of a parallel code into a memory unit. It can :be used for the purpose of automatic control or may be fed to a decoder for transforming the code into the decimal system and for registering the readings of the instrument.

The read out of the instrument readings, remote transmission of the data and recording of the readings are effected during the brief flash period of the tube and the simultaneous rotation of the loop with the mirror mounted on it.

This makes it possible to obtain data even on high-speed processes by a sequential triggering of several converters of this type connected to various transducers.

Utilization of the converter described in the present invention will result in considerable economy as it will help to reduce the production cost of each unit and will allow to develop multipoint systems operating on the :principles of pulse-code telemetry characterised by the highest degree of stability of operation.

What we claim is: 9

An optical converter of an angular shaft position into a pulse serial code comprising a control shaft; a coding disk having radially disposed two-dimensional code patterns thereon coupled to said control shaft; a gas-discharge tube having a light emission exposed through said coding disk, a single semiconductor photodiode; an armature; a mirror mounted on said armature; an optical system for compressing the light from said gas-discharge tube after it has exposed a \portion of the code patterns on the disk and for projecting it onto said mirror; means for causing said mirror to spatially scan the two-dimensional code pattern light; said means including a series connection With said gas-discharge tube and a power source to energize the armature only during the light emission of the gas tube to establish movement of the armature relative to the disk; said |photodiode disposed for sensing the scanned light patterns; and apertured means interposed between the mirror and the photodiode to select a predetermined radial level of the code patterns for passing, as modulated light in accordance with the said patterns, to said photodiode.

References Cited by the Examiner UNITED STATES PATENTS 0 MAYNARD R. WILBUR, Primary Examiner.

MALCOLM A. MORRISON, Examiner.

D. W. COOK, K. R. STEVENS, Assistant Examiners. 

